This invention relates to slot seal closures and more particularly to closures for a slot formed in the side of an aircraft fuselage, adjacent an inboard wing trailing edge flap.
In certain types of flap systems, the inboard wing flap has a torque tube which extends into the side of the fuselage or into the side of a fuselage/wing fairing structure; and the inboard end of this flap torque tube is mounted to a flap carriage mechanism for controlled movement of the flap throughout its extension and retraction cycle. This inboard flap carriage mechanism is located within the fusefage or within the fuselage/wing fairing structure; and in the aircraft installation of the present invention, it is located within the main landing gear wheel well.
The inboard flap carriage mechanism is designed to move the inboard flap and its torque tube along a predetermined path which is generally arcuate or curved, and this requires a similar arcuate or curved slot in the side of the fuselage to accommodate translational movement of the flap torque tube during flap extension and retraction. When the flaps are in a fully retracted position, the root end cross-sectional area of the inboard flap and a root end plate adequately cover the curved slot in the side of the fuselage. However, when the flaps are fully extended and the wheels are down for the landing mode, the curved slot is exposed and there is an airflow therethrough that flows spanwise into a low pressure region on the upper surface of the extended inboard flap, that effects separation of the boundary layer airflow over the upper surface of the flap. The problems caused by this initially appeared as numerous incidents of the fuselage tail section striking the runway during the landing flare out just prior to touchdown. Another problem caused by the exposed flap torque tube slot was a vibration that was felt by the pilots just prior to touchdown with full flaps. Numerous flight tests were conducted to solve the problems, and they conclusively indicated that the problems were caused by the lack of a seal for the curved slot in the side of the fuselage when the landing gear and flaps were down for the landing mode. Various attempts were made to seal the curved slot; first with brushes, and when one brush did not provide an adequate seal, then two or three brushes were tried without success.